Building SafeguardsBuilding managers are protecting their employees from what they predict might be the next version of anthrax attacks: anthrax spores in ventilation systems. Some government, media and other office buildings are upgrading their ventilation systems, installing filtered "safe havens," and taking other concrete steps. NPR's Daniel Zwerdling reports.

Building managers are protecting their employees from what they predict might be the next version of anthrax attacks: anthrax spores in ventilation systems. Some government, media and other office buildings are upgrading their ventilation systems, installing filtered "safe havens," and taking other concrete steps. NPR's Daniel Zwerdling reports.